RESUMO
ObjectiveTo analyze the dynamic changes of the main chemical components and color characteristics of Polygoni Multiflori Radix（PMR） during the process of ancient classical nine-time repeating steaming and sun-drying， and to explore the correlation between the changes. MethodHigh performance liquid chromatography（HPLC） was used to determine the contents of gallic acid， stilbene glycoside， emodin-8-O-β-D-glucoside， physcion-8-O-β-D-glucoside， emodin and physcion in PMR during the process of nine-time repeating steaming and sun-drying， and electronic eye technology was used to objectively characterize the color of PMR during the process. Partial least squares（PLS） was used to analyze the correlation between the content of main components and the color characteristics. ResultDuring the nine-time repeating steaming and sun-drying process of PMR， the content of gallic acid gradually increased with the increase of steaming and sun-drying times， and the contents of other components showed fluctuating changes， with an overall decreasing trend in the contents of stilbene glycoside， emodin-8-O-β-D-glucoside and physcion-8-O-β-D-glucoside， and an overall increasing trend in the contents of emodin and physcion. The results of electronic eye analysis showed that the color of PMR became dark， red and blue in the process of nine-time repeating steaming and sun-drying. The results of hierarchical cluster analysis（HCA） and principal component analysis（PCA） of the contents of six main components and the colors showed that the samples steamed and sun-dried for one to four times could be grouped into one category， the other five categories of samples could be grouped into another category. Gallic acid and stilbene glycoside were significantly correlated with the color indexes of PMR during the process of nine-time repeating steaming and sun-drying. ConclusionThe general changes of material basis and color characteristics of PMR during the process of ancient classical nine-time repeating steaming and sun-drying have certain rules， and the establishment of the correlation model between color and index components can realize the judgment and quality evaluation of processing degree of PMR decoction pieces.
RESUMO
The purpose of this study was to evaluate the color changes of the composite resin resulting from xenon lamp exposure in different environments. Composite resin (Z 250 ; shade A1, A2, A3, A3.5, and A4) were applied in a cylindrical metal mold. Seventy five specimens according to environments of exposure were made as follows; Group I: aluminum foiling of the specimens in the air at 37degrees C for 1 day and 7 days. Group II: exposure of xenon lamp to the specimens in the air at 37degrees C for 1 day and 7 days. Group III: exposure of xenon lamp to the specimens in distilled water at 37degrees C for 1 day and 7 days. The color characteristics (L*,a*,b*) of the specimens before and after exposure of xenon lamp were measured by spectrophotometer and the total color differences (DeltaE*) were computed. The results obtained were as follows: 1. In all groups except A1 shade of group III, the DeltaE* values presented below 2.0, and group III showed the highest DeltaE* values followed by group II and group I in a decreasing order(p<0.05). 2. In all shades and groups, the more the exposure time of xenon lamp and the lighter the shade were, the higher the tendency for discoloration (p<0.05). 3. The composite resins which was exposed to xenon lamp in the distilled water was more discolored than those in the air (p<0.05). 4. The major changes of composite resins which were exposed to xenon lamp in the air were an increase in yellowness through a positive shift of the b* value, and those in the distilled water were an increase in darkness and yellowness through a negative shift of the L* value and a positive shift of the b* value.